Locking buckle



FIG. 1 is a perspective view of a locking buckle showing the new design;

FIG. 2 is a right side view thereof;

FIG. 3 is a left side thereof;

FIG. 4 is a front side view thereof;

FIG. 5 is a back side view thereof;

FIG. 6 is a bottom view thereof; and,

FIG. 7 is a top view thereof.

The broken line portions of the disclosure are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a locking buckle, as shown and described herein. 